(a) Field of the Invention
The present invention concerns a container, of the type including at least one shell defining interior volume, the shell including a main part to contain at, least one liquid, peripherally bound by an outer wall, and an end part defining a duct giving access to the interior volume and whose transverse dimensions are smaller than those of the main part, removable shutter means to close the access duct, and level detecting means providing a signal which is representative of a level of liquid in the main part of the shell.
The present invention concerns any type of liquid container with a coefficient of electrical conductivity which differs from that of the gaseous atmosphere above the liquid in the shell of the container and requiring an access to the interior volume of the container, and more particularly cryogenic liquids, for example, although not exclusively, for the storage of biological products in a cryogenic liquid, such as liquid nitrogen.
(b) Description of Prior Art
It has also been proposed to provide mechanical or electrical means, which can detect a level, and are in the shape of a rod extending into the shell through the access duct. This technology however has the disadvantage of requiring the detecting means to be removed to free the access to the interior volume, even if only to fill the shell. The fact that the detecting means can be removed creates problems of installation and calibration and, in particular, in cryogenic containers, problems of trapping humidity which frequently causes interruptions of the detecting means when they are reintroduced into the cold enclosure. In the field of cryogenic containers for biological products, it has on the other hand been proposed to provide ultra-sonic protecting means which are carried by the shutter means, according to an approach which is costly and however not very reliable.